Variable-resistance device



Feb. 7, 1928. 1,658,666

c. E. BURGENER ET AL VARIABLE RES I S TANCE DEVI CE Filed Dec. 6. 1926 3 3 2K 9 O 38 32 Z6 M ,7 Ham 2/ /9 $441.!!! 0 iiii Z 5 l I/ Z a 7 T F i 1 91.4.

6 3/ 3 gvvuenfozs 7 32 A6 I M Charles E BIJWE/YER J- RALPH M. HARMC This invention relates to improvements in devices for measuring pressure and has reference more particularly to a clevice fo cletermining by electrical means the air'pressure in automobile tire.

" 's Well known to all who are familiar in with L118 operation of automobiles that slow leaks will frequently develop; these are E is o'o eca oi; this Hit- 61351631 to i .0 H ,{iVlCE which Will inoicet-e we r in each tire nideoeii en ly toy means 01 3 s dial and a eointer located Oil cue instrunevtcn.

inversely as the pressure in the tube 7. This rheostat is formed from a base 9 of insulating material such as fiber, hard rubber or any other suitable material. This base is preferably enclosed in a, casing 10 which has one side open and whose ends are provided with outwardly extending ears 11, which are perforated for the reception of screws 12 by means-of which the casing is secured to the Base 9 has a longitudinal channel 13, provided near one and with shoulder or elevatecl surface i l to which the list spring; 15 is fastened by means of clezesp ing bolt 16. The end of this belt to which the nut is applied lies in the cut out 1? anti forms it terminal for the conductor 18. The bottom surface 19 of the channel 13 has a ".SVQTSG ZeCeSS 20 Within which locateii it e ai plate 21 from one side of which threaded pin 22 projects This termiates in the cut out or recess 23 and serves inent bostci Where they can seen ruiinal for the condu tor The ti by th ccupants oi the machin s ace of plate 21 15 covered. with a which therefore makes possible for formecl "from cai'bon snci shellso. to determine the condition of the sicc'oate metal ssi'ing 26 is secuted with to discover any faulty condition before clai'nege resultetl. v

Our invention can be best tlesceibeci sncl "will be most reeclily LlfiClSiSiZOOCl when T.eif8?-= its comer; sicle against the bottom surface 19 ancl held in place by means of e bolt 27'. An adjusting; screw has 2: threes-led connection with the heel member ,ncl en- {sages the enti of the spi'iv i nennes shown in Fig. 2. l s1 26 that is opposed to the 5311-8108 es coy-- 2; i'filXtlilS liustreteii a ncl in which: I

l View T elevation snowi our invention in erecl with a layer 2? oi? carbon ens. shellac.

Z25 connection wi .i b es the encl o c i pin 32 extenfis througn are. rim and terminates in a .at h which the outer so rests.

of spring 15. i 1 io'rce exertei by the "within the inner tube F iiuinesai TL designates portion of e front pin 31 outWat-clly q "file of automobile sncl Q spindle arm springs 15 and 2t} and iet the which the ront wheel 3 is attached, While an amount clicectlyprop r lonal LO 1 is in fiifillt hostel. sure Within the tube. ih

as the usual 5 to which effect, a spring balance Those 0 able sin: i5 is secueetl in the a pos tion of equilibriun wh m 1s the ent i6? 2W he inns: T and for pressu' eh is evident that en a 1 constfuction. tie pressure it I or parts lg out I inven ion ve combine cause "he ign t en 'uc with the \eiountable rim tube and and t the so? casino a rheos face QQ nli co 2 the cor to allfii so connected and as oca e l with the Tim respomnng su e in the tube cesuig that 1 etc nice will very Contact area o and we increased pressure reduces the electrical resistance and permits a greater amount of electrical current to flow from the battery B through conductors 18- and 24 to and through the ammeter Athat is connected in series with the particular rheostat. The reading of the ammeter will therefore n1- crease as the air 'ressure in the tire increases and its reading will therefore indicate pressure. Byproperly calibrating the scale of the ammeter, the readings can be made to represent the actual pressure in the tire at any time. 7

Since the wheels rotate and the ammeters A are stationary, it is, of course, necessary to provide a connection through which current may be conducted to the rheostat. For this purpose we have provided a ring 33 of conducting material which is secured to the wheel by means of an annular insulating ring 34. A conductor 18 is connected with this ring and conductor 24 is grounded. A brush 35 is supported from the spindle arm by suitable insulating means and .contacts with the ring so as;.to form a slip ring contact, through which current may be transmitted to the-rheostat when the wheel .rotates. The sli scribed is inten ed merely as an example of a means that can be used and it may be replaced by any other means that is suitable or the purpose.

The rheostat that has been described is constructed on the principle ofthe ordinary :arbon pile and is intended merely as an illustration of a means, for it is evident that many specifically difi'erent constructions can be employed, the only requirement being that the resistance shall change either indirectly or directly with the pressure in the tire.

Since the source of current employed is. a,

storage battery, the voltage will be substantially constant and therefore the variations in the current will be due to the variations in the resistance only.

The amount of current flowing through ammeter A can be controlled by the addition of a constant resistance in the circuit. It is desirable to have only a small amount of current fiowingthrough the device in order not to cause a too large drain on the storage battery.

From the above it will be apparent that we have roduced an electrical pressure indicating evice by means of which the pressure at any point can be used for controlling an indicator at a distant point and by ring connection just de-' means of this simple combination of elements described we have been enabled to obtain a continuous and reliable indication on the instrumentboard of the pressure in each of the four separate tires on an automobile.

It is evident that our device can be employed for many other uses and the one described is illustrative only.

Having thus described the invention, what we claim as new is: a

;1. A variable resistance device comprising, in combination, a base of insulating material, said base having a longitudinal recess in one side, an electric contact extending through I the bottom of the'recess, said contact having its inner end provided with .a layer of carbonaceous resistance material, an arcuate springhaving one end secured, to the base at one side of the contact, the convex end of said spring being provided with a layerof carbonaceous resistance material, said sprin being secured tothe base with its convex side towards the base and means for adjusting the position of said spring.

2. A variable resistance device comprising,

in combination, a base of insulating material,

said base having a longitudinal recess in one side, an electric contact extending through the bottom of the recess, said contact having its 1nner end bonaceous resistance material, an arcuate one side of the contact, the convex end of said spring being provided with a layer of carbonaceous resistance material, said spring being secured to the base with its convex side towards the base and means for straighten ing the spring. p

I 3. A variable resistance device comprising, in combination, a base of insulating material, said base having a longitudinal recess in one. side, an electric contact extending adjusting the position of, said spring and means for straightening the spring.

In testimony whereof we affix our signatures. v

' CHARLES E. BURGENER.

' RALPH M. HARMON.

provided with a layer of car-.

' spring having one end secured to the base at V 

